The present invention relates to the art of interactive image-guided surgery and interactive surgical planning. It finds particular application in conjunction with the planning and implementation stages of minimally invasive stereotactic surgical procedures performed in CT imaging systems using a localization device to orient a surgical tool such as a brachytherapy needle or the like for planning and placement of objects within the body of a patient, and will be described with particular reference thereto. It is to be appreciated, however, that the invention is also applicable to a wide range of imaging equipment and techniques, for example ultrasonic and magnetic resonance imaging devices, and to a broad range of minimally invasive surgical procedures including many forms of surgery for placing objects at precise points within a patient such as interventional radiology procedures and others.
In certain surgical procedures, there is a need to place one or more objects at precise locations within the body of a patient. Examples of these procedures include techniques for placement of dental implants or other orthopedic supports or structures within a patient. One broad class of procedures that requires placement of objects within a patient are found in the interventional radiological arts. One such form of radiation therapy is brachytherapy in which radioactive seeds are inserted into cancerous tissue, thereby attacking cancer cells. In brachytherapy, as with other forms of radiation therapy, it is desirable that the seeds be distributed within the malignant tissue in a particular pattern according to a selected dose distribution plan. It is generally desirable that the seeds be distributed evenly so as to avoid hot (e.g., over-radiated), and cold (e.g., under-radiated) spots. Additionally, the seeds should not be placed outside of the target region. One method for inserting the seeds in the case of prostate brachytherapy involves trans-rectal ultrasound image guidance. One disadvantage of such a procedure, however, is that preoperative planning and visualization information is limited. Also, the procedure is uncomfortable for the patient.
Certain dose planning, preoperative planning, and post operative verification techniques have been proposed in radiation therapy to overcome the above disadvantages, particularly the lack of visualization information. In one example, the patient is first scanned to generate a volumetric image data set. Thereafter, the collected patient image data set is forwarded to an off-line dose planning system. On a remote computer, virtual xe2x80x9cseedsxe2x80x9d are placed on axial view-graphs of the patient derived from the patient image data set to provide a virtual prescribed cumulative seed distribution. The location of the virtual seeds in x, y, z coordinates in the patient""s image data set are stored so that when the patient is repositioned on the scanning apparatus, sometimes days later, the physical radioactive seeds can be introduced into the body of the patient at the physical x, y, z coordinates corresponding to the x, y, z coordinates defined by the virtual seeds that were xe2x80x9cplacedxe2x80x9d during the off-line planning stage.
One disadvantage with the above approach, however, is that the trajectories defining the insertion path(s) for introducing the seeds through the skin of the patient for travel toward the target site(s) are not taken into consideration in the planning stage. Accordingly, it is very difficult to plan multiple seed deposits along a single trajectory thereby increasing the number of required needle insertions during the plan implementation phase thus increasing the associated morbidity. A lack of trajectory visualization also jeopardizes critical anatomical structures that lie between the skin and the target point.
In addition to the above, during the implementation phase, the patient must be re-scanned in the imaging apparatus, typically days later. In the likely event that the patient is not relocated onto the imaging apparatus in the position in which the patient was scanned to develop the x, y, z seed target locations during planning, the initial dose plan becomes unreliable and is therefore no longer valid. A similar disadvantageous result obtains when the tumor or other target tissue within the patient moves between the pre-operative planning scan and the implementation phase. In either case, the brachytherapist is provided with no means to adopt a new plan or otherwise adjust the original plan.
There is a need, therefore, to provide a method and apparatus for planning and executing minimally invasive procedures for in-vivo placement of objects that enables non-invasive pre-operation virtual seed placement and dose distribution planning using visualization information showing a patient""s anatomy together with a set of single point targets within the patient""s body and a corresponding set of trajectories through the skin and body of the patient leading to the target points.
Further, there is a need to provide a method and apparatus for planning interventional radiological procedures that provides dose distribution visualization information so that the planning interventionist can quickly and easily derive a dose plan strategy commensurate with a pathological prognosis of the patient as determined from the patient""s pre-operative volumetric image data set. Preferably, the visualization information includes a cumulative dose distribution volume defining a plurality of dose level contours surrounding each virtual seed for visualization in slices taken through the patient""s image volume data set at various selected angles and orientations. The dose plan preferably includes visualization information showing a prescription dose profile as well as a low dose profile surrounding the virtual seeds.
Preferably, the method and apparatus further includes a localizing device for implementing the dose plan by providing a means for precisely aligning an interventional tool along each of the one or more planning trajectories so that the radioactive seeds can be inserted at each target point and along each planning trajectory in turn according to the previously derived plan. Preferably, the method and apparatus provides visualization information in the form of at least two axial image slices showing the virtual needle entry point and target point, as well as a pair of multi-planar reformatted (MPR) image views of the patient""s image data set along the trajectory of a virtual needle, each view being combined in an overlayed fashion with the dose distribution volume data set of the patient. This enables an interventionist to align the interventional tool carried on the localizing device with the virtual trajectories developed during the planning stage. The interventionist moves the localizing device and interventional tool into a range of positions relative to the patient until the multiple views of the physical tool shown on the display device are in alignment with the virtual trajectories shown on the display device and developed during the planning stage. Once aligned, the localizing device is selectively locked in place relative to the patient so that the interventional seed carrying tool can be translated along the planning trajectory to a desired depth for precise placement of the radioactive seed or other selected object within the patient""s body.
In accordance with the present invention, a method and apparatus for planning a minimally invasive procedure for in-vivo placement of an object within a patient is provided.
In accordance with a more detailed aspect of the invention, a method and apparatus for planning and executing a minimally invasive procedure for in-vivo placement of an object within a patient is provided.
In accordance with yet a more detailed aspect of the invention, a method and apparatus of planning a minimally invasive procedure for in-vivo placement of a plurality of objects within the body of a patient is provided.
In accordance with yet a still more detailed aspect of the invention, a method and apparatus for planning and executing a minimally invasive procedure for in-vivo placement of a plurality of objects within the body of a patient is provided.
The preferred method of planning placement of objects within the body of a patient includes scanning the patient includes scanning the patient in an imaging device to generate a volumetric image data set of the patient. Thereafter, an image of the patient derived from the volumetric image data set is displayed on a human readable display device. A virtual target point is selected in the image of the patient by identifying a first set of virtual coordinates in the patient image. A virtual trajectory for inserting an object into the patient is selected by identifying a virtual path extending from the selected virtual target point and out from the body of the patient. Lastly, the virtual trajectory is displayed on the human readable display device together with the image of the patient. Preferably, the patient image is a multi-planar reformatted image and the image is coincident with the virtual trajectory so that the entire trajectory is visible on the display device.
The preferred apparatus for planning placement of objects within the body of a patient includes an imaging device for scanning the patient to generate a volumetric image data set of the patient. A human readable display device displays an image of the patient derived from the volumetric image data set. Processing means together with a control console are provided for selecting a virtual target point in the image of the patient and for selecting a virtual trajectory for inserting an object into the patient. The virtual target point is identified on the display device by selecting a first set of virtual coordinates in the image of the patient. The virtual trajectory is selected by identifying a virtual path extending from the selected virtual target point and extending outwardly from the body of the patient image. Lastly, a display means is provided for displaying the virtual trajectory on a human readable display device together with the image of the patient. Preferably, a multi-planar reformatted image of the patient is generated and the virtual trajectory and the planar image of the patient are coincident.